Abstract
Safely and effectively eliminating pathogens from surfaces without causing harm to patients, health care staffs, or capital equipment can be incredibly challenging, especially with pathogens like C. difficile and C. auris. Traditional disinfecting chemicals, such as quatermonium compounds (“quats”), peracetic acid mixtures, phenols, and sodium hypochlorite (bleach), are notoriously irritating to eye, nose, and throat tissues, corrosive to human tissues and equipment alike, and have varying degrees of efficacy against the array of pathogens they are employed to kill. To make matters worse, these chemistries are not effective against biofilms that protect pathogens and allow them to multiply unopposed. Fortunately, a very safe, eco-friendly, and extremely effective alternative exists: hypochlorous acid (HOCl). In this article, we will explore the safety, efficacy, pros, and cons of hypochlorous acid and why you may want to consider adopting it in your facility.
Main Article
Pathogens come in a variety of forms such as enveloped and non-enveloped viruses, gram-positive and gram-negative bacteria, and fungi. Many of these pathogens, such as C. difficile and C. auris, are difficult to kill with traditional disinfectants, and not every disinfectant is capable of killing all of these types of pathogens. Adding to the complexity is the fact that many pathogens survive and thrive in biofilms that these disinfectants cannot eliminate or even penetrate (Weber et al, 2023). Two well-proven, safe, and extremely efficacious disinfectants do exist that do not have these shortcomings: hypochlorous acid (HOCl) and chlorine dioxide (ClO2). Of the two, hypochlorous acid is the much safer, more practical, and more economical choice to use in a healthcare setting, and it can replace all types of disinfectants that are currently used in a given facility.
While hypochlorous acid is a relative newcomer to the infection prevention scene, it has been around since the beginning of humanity, and the dawn of mammals for that matter. In fact, the human body (and other mammalian bodies) produces its own HOCl to fight infections (Andres et al, 2022). HOCl has been around in manufactured form more recently in products for wound care and ophthalmological infection treatment, as well as water treatment and other industrial sanitation purposes (Block, 2020). The advantages of HOCl for healthcare surface disinfection are abundant and are now being proven: very high efficacy against all known types of pathogens, the ability to destroy biofilms and the pathogens they protect, high safety even in high concentrations, environmentally friendly chemistry, non-corrosive and non-staining oxidizing activity, elimination of noxious odors, mild bleach-like odor, and the ability to safely produce large volumes onsite and on-demand from water, salt, and electricity. This on-demand production is the optimal way to obtain HOCl as it has a relatively short shelf-life. Chlorine dioxide also has a short shelf-life but is also a toxic gas that is too dangerous to be produced onsite. Chlorine dioxide is generally only produced in large industrial settings like water treatment and wood pulp bleaching plants, and shipped as an RTU (ready to use) product or in tablet form to be diluted with water onsite. Most hospitals that have adopted HOCl are using it in spray bottles and electrostatic sprayers and replacing their multitude of purple top, red top, and other wipes with HOCl-filled canisters of wipes, thus simplifying inventory and infection prevention compliance.
pathogens and biofilms are destroyed rather than poisoned, which is the primary means of action for most disinfectants
The safe oxidative power of hypochlorous acid is what sets it apart from other disinfectants, even other oxidizers such as hydrogen peroxide and bleach. Rather than oxidizing indiscriminately like hydrogen peroxide and bleach do, HOCl reacts “selectively” with sulfur-based compounds such as amino acids and noxious sulfur compounds and breaks those chemical bonds (Pereira et al, 1973). The result is that pathogens and biofilms are destroyed rather than poisoned, which is the primary means of action for most disinfectants. This helps to prevent pathogens from developing resistance to it, and it accounts for why HOCl does not damage human tissues in normal concentrations, and it does not compromise plastics, metals, electronics, or other materials. Pure hypochlorous acid solutions do not leave unsightly residues on surfaces, and they will not damage or dull floor finishes when used to disinfect floors. Because HOCl that is generated onsite does not require the addition of surfactants or buffers to help in the “wetting” of the surface or extend shelf life slightly, it also does not leave behind residues from added ingredients.
Hypochlorous acid can be shipped as an RTU solution, typically containing buffers and/or surfactants, but it is easier and more economical to make on site with a dedicated hypochlorous acid generator such as the HAI Prevention Program generator offered by Sanitis. Such a generator is a self-contained, low maintenance system that provides for traceable production and expiration data for each batch and continuous off-site monitoring by the manufacturer to ensure that the machine is operating at peak efficiency and reliability. This system is capable of generating five hundred gallons of hypochlorous acid per day, as compared to many systems that only produce small volumes at a slow pace, making them inadequate for the needs of most hospitals.
While the short shelf life of hypochlorous acid has hampered its adoption on a large scale in the past, recent advances in HOCl generator technology have made it the preferred disinfectant at some of the most highly respected hospitals and hospital systems. These hospitals can generate as much HOCl as they need when they need it, and they are assured that one eco-friendly disinfectant meets all of their disinfection needs. Their patients and staff are safe from dangerous and noxious chemicals, and compliance is greatly simplified. With the advantages provided by this disinfectant chemistry, it is a clear choice for health care facilities seeking to mitigate the potential damage, dangers, and shortcomings in efficacy that are inherent in traditional disinfectant chemistries.
References
Andrés, C. M., Pérez de la Lastra, J. M., Juan, C. A., Plou, F. J., & Pérez-Lebeña, E. (2022). Hypochlorous acid chemistry in mammalian cells—influence on infection and role in various pathologies. International Journal of Molecular Sciences, 23(18), 10735. https://doi.org/10.3390/ijms231810735
Block, M. S., & Rowan, B. G. (2020). Hypochlorous acid: A Review. Journal of Oral and Maxillofacial Surgery, 78(9), 1461–1466. https://doi.org/10.1016/j.joms.2020.06.029
Pereira, W. E., Hoyano, Y., Summons, R. E., Bacon, V. A., & Duffield, A. M. (1973). Chlorination studies II. the reaction of aqueous hypochlorous acid with α-amino acids and dipeptides. Biochimica et Biophysica Acta (BBA) – General Subjects, 313(1), 170–180. https://doi.org/10.1016/0304-4165(73)90198-0
Weber, D. J., Rutala, W. A., Anderson, D. J., & Sickbert-Bennett, E. E. (2023). Biofilms on medical instruments and surfaces: Do they interfere with instrument reprocessing and surface disinfection. American Journal of Infection Control, 51(11). https://doi.org/10.1016/j.ajic.2023.04.158
